A method for calibrating a radio frequency (RF) transmitter to compensate for a frequency-dependent in-phase quadrature (FDIQ) mismatch is disclosed. The method may include determining in-phase quadrature (IQ) amplitude and phase mismatches of the RF transmitter for a lower side band (LSB) and an upper side band (USB), determining a FDIQ mismatch based on linear fitting the IQ amplitude and phase mismatches for the LSB and the USB, modifying the FDIQ mismatch based on flipping a FDIQ phase mismatch in the LSB and flipping a FDIQ phase mismatch in the USB to generate a modified FDIQ mismatch, determining Fourier coefficients based on applying an inverse fast Fourier transform to the modified FDIQ mismatch, and determining FIR coefficients for a finite impulse response (FIR) filter of the RF transmitter based on windowing the Fourier coefficients.
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3. The method of claim 2, wherein the FIR filter is included in an IQ mismatch compensation module of the RF transmitter.
4. The method of claim 3, wherein the IQ mismatch compensation module receives signals from a RF digital pre-distortion (DPD) module of the RF transmitter and outputs signal to an I path baseband DPD module and a Q path baseband DPD module of the RF transmitter.
5. The method of claim 1, wherein the flipping the FDIQ phase mismatch in the LSB includes regenerating a FDIQ phase mismatch from frequencies −fs/2 to −fs/4 based on flipping a FDIQ phase mismatch from frequencies −fs/4 to 0 Hertz and the flipping the FDIQ mismatch in the USB includes regenerating a FDIQ phase mismatch from frequencies fs/4 to fs/2 based on flipping a FDIQ phase mismatch between frequencies 0 Hertz to fs/4, wherein fs represents a sampling rate of the FIR filter.
8. The method of claim 1, wherein the windowing uses a Hamming window.
9. The method of claim 1, wherein the IQ amplitude and phase mismatch for the LSB is determined at a frequency of −400 kilohertz (kHz) and the IQ amplitude and phase mismatch for the USB is determined at a frequency of +400 kHz.
12. The non-transitory machine-readable storage medium of claim 11, wherein the FIR filter is included in an IQ mismatch compensation module of the RF transmitter.
13. The non-transitory machine-readable storage medium of claim 12, wherein the IQ mismatch compensation module receives signals from a RF digital pre-distortion (DPD) module of the RF transmitter and outputs signal to an I path baseband DPD module and a Q path baseband DPD module of the RF transmitter.
14. The non-transitory machine-readable storage medium of claim 10, wherein the flipping the FDIQ phase mismatch in the LSB includes regenerating a FDIQ phase mismatch from frequencies −fs/2 to −fs/4 based on flipping a FDIQ phase mismatch from frequencies −fs/4 to 0 Hertz and the flipping the FDIQ phase mismatch in the USB includes regenerating a FDIQ phase mismatch from frequencies fs/4 to fs/2 based on flipping a FDIQ phase mismatch between frequencies 0 Hertz to fs/4, wherein fs represents a sampling rate of the FIR filter.
17. The non-transitory machine-readable storage medium of claim 10, wherein the windowing uses a Hamming window.
18. The non-transitory machine-readable storage medium of claim 10, wherein the IQ amplitude and phase mismatch for the LSB is determined at a frequency of −400 kilohertz (kHz) and the IQ amplitude and phase mismatch for the USB is determined at a frequency of +400 KHz.
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May 11, 2023
December 31, 2024
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